Hydraulic elevators



1967 K. R ROSENBERG HYDRAULIC ELEVATORS Filed March 4, 1966 I N VEN TOR.Kf/VMEf/flg flax/vane Jrramvzkf United States Patent C 3,302,753HYDRAULHI ELEVATORS Kenneth R. Rosenberg, 8536 N. Pelham Parkway,Milwaukee, Wis. 53217 Filed Mar. 4, 1966, Ser. No. 531,895 6 Claims.(Cl. 1871) This invention relates to improvements in hydraulicelevators, and more particularly to a novel safety device which isadapted to prevent the entry of water into the hydraulic oil system ofan elevator.

Hydraulic elevators of the type herein concerned include an elongatedcylinder or plunger housing which extends downwardly below the basementor lower level of the building, and an extensible ram or plunger carriedin and projecting above said cylinder is designed to raise and lower theelevator cab through the actuation of a hydraulic pump assembly, therebeing a shallow pit adjacent said cylinder to house other necessarycomponents. Unfortunately, after a period of use it is not uncommon thatthe packing and sealing members surrounding the extensible plunger andother movable elements become worn and oil leaks from the hydraulicsystem and accumulates in the pit, thus fouling the pit and affectingthe safe operation of the elevator. To overcome this objectionablesituation, most modern elevators have a ring member mounted on andsurrounding the upper end or head of the cylinder which is designed tocollect oil which leaks from the system and runs down or drips from theplunger, and mounted therebelow is a tank or reservoir which is adaptedto receive the leakage oil from said collecting ring. A float-typeswitch is carried within said oil return reservoir and is so designedthat when the accumulated leakage oil reaches a certain predeterminedheight in said reservoir a pump is actuated to return said oil to thehydraulic system of the power unit, thus ensuring that there is always asufficient quantity of oil in the system to perimt safe operation of theelevator.

Such conventional safety devices are satisfactory for their intendedpurpose but, unfortunately, one of the greatest dangers in hydraulicelevators is that water which forms on the plunger as condensate, orsurface water which finds its way into the area, will enter the oilreturn reservoir and be pumped into the power unit hydraulic system,Where it will saponify the oil. In such instances when the jelly-likesaponified oil is circulated in the hydraulic system it can clog thefilter and valve members and cause a failure which can result inuncontrolled movement of the elevator. Such occurrences are notuncommon, and have been the cause of tragic accidents.

With the above in mind, the principal object of the present invention isto provide a novel sensing device for mounting in the oil returnreservoir of a hydraulic elevator system which is adapted to detect thepresence of water in said reservoir. In the event water is present saidsensing device is designed to automatically actuate an associated switchto halt the operation of the oil return pump, thereby preventing saidwater from being pumped into the power unit hydraulic system, and theoperation of the elevator is also halted, except to allow said elevatorto descend to the lowermost level to discharge its passengers.

A further object of the present invention is to provide a novel safetydevice adapted to prevent the entry of water into the oil system of ahydraulic elevator, as de scribed, which device is relatively simple andinexpensive ice in design and construction, which is reliable inoperation, and which device is otherwise particularly well adapted forits intended purposes.

With the above and other objects in view, which other objects andadvantages will become apparent hereinafter, the invention comprises theimproved elevator safety device described in the following specificationand also any and all modifications or Variations thereof as may comewithin the spirit of said invention, and within the scope of theappended claims.

In the accompanying drawings, wherein there is illustrated one preferredembodiment of the invention, and wherein the same reference numeralsdesignate the same parts in all of the views:

FIG. 1 is a perspective view showing the oil-collecting ring, returnreservoir, and the control housing, with a part of said housing brokenaway to show the Water-sensing device and associated components mountedtherein; and

FIG. 2 is a front elevational view of the water-sensing probe devicefeatured in the present invention.

Referring now more particularly to FIG. 1 of the drawings, the numeral10 designates the steel flange or ring which is rigidly mounted insurrounding relationship on the head portion of the plunger cylinder(not shown) in conventional hydraulic elevators. As hereinabovementioned, said ring 10 is designed to collect oil which might leak fromthe hydraulic system and drip or flow downwardly on the plunger, asfrequently happens when the plunger oil seals and packings become worn.Secured on said collecting ring 10 by means of bolt and nut assemblies11 are a pair of depending support brackets 12, and suspended thereon isa return oil reservoir 13 and control housing 14. Extending downwardlyinto said reservoir 13 from the collecting ring 10 is a tube 16 which isdesigned to direct the leakage oil accumulating in said ring downwardlyinto said return reservoir.

Mounted within said reservoir housing 13 is a float switch 17 which isvertically-adjustably suspended from the top of said housing, said floatmember having an upright rod portion 19 which projects upwardly into thecontrol housing 14, and also carried within said oil return reservoir isa centrifugal pump 18 having a motor 28. Carried within the controlhousing 14 is a mercury switch assembly 21, enclosed relay 29, and relayterminal block 15, which are operatively connected to a suitable sourceof electric power, and in the complete assembly a cover is provided forsaid housing.

In the operation of hydraulic elevators of the type here involved, whenleakage oil from the collecting ring 10 is deposited in the reservoir 13it accumulates therein and as the level of said oil rises the float unit17 rises therewith. When a predetermined volume of oil has accumulatedWithin said reservoir the upright rod 19 on said ascending float unitengages and tips the pivotally-mounted switch 21 in the control housing14. Upon the engagement of said mercury switch 21 the pump 18 in thereturn oil reservoir is actuated and commences pumping said accumulatedleakage oil back into the elevator hydraulic system. When said floatreturns to its original level the switch 21 pivots back to its normalposition and the pump shuts off.

The above-described float switch. and pump assembly is conventional inmany modern hydraulic elevator installa- As hereinabove mentioned,however, conventional hydraulic elevators do not have means fordetecting the presence of Water in the oil return reservoir, and thiscan be a source of considerable trouble. If water finds its way into thereturn oil reservoir and is pumped into the hydraulic system it willsaponify the oil and seriously impede the operation of the valves andother components, which can result in uncontrolled movement of theelevator. Not only is there always the danger of Water from a burstWater pipe or flood water in a building, but on hot, humid days asubstantial quantity of water in the form of condensation forming on theplunger can create a hazard.

In accordance with the present invention there is mounted Within the oilreturn reservoir 13 an electrical probe element which is designatedgenerally by the numeral 22. As best appears in FIG. 2, said probe 22includes a plastic intermediate portion 29 and a tubular body 23 formedof a suitable insulating material, the upper end of which is threadedand secured to the housing by a nut 27 (FIG. 1). Mounted in andprojecting downwardly from said intermediate portion are a pair ofspaced parallel copper arms 24 and 25 forming the electrodes of saidprobe, and soldered thereto and extending upwardly within said hollowbody member 23 are electrical lead wires 26 which are connected to therelay mechanism in the control housing 14.

In the use of the present invention, when the elevator system isoperative an electric current of predetermined value is constantlydirected through the probe electrodes 24 and 25. Since oil is a poorconductor of electricity, however, the intensity of the current passingbetween said electrodes when the latter are immersed in oil is minimal.However, in the event water finds its way into the oil return reservoirand said downwardly-extending probe electrodes 24 and 25 are immersed orpartially immersed in water, which is a relatively good electricalconductor, there will be a substantially-increased current flow. Saidincreased current flow through the probe electrodes is designed toenergize the relay 20 which functions to prevent the operation of thepump 18, thereby eliminating the possibility of the water in saidreservoir being pumped into the power unit hydraulic system.Simultaneously, said relay actuates a control switch which functions toprevent upward travel of the elevator, said elevator automaticallydescending to its lowermost level in order to permit the discharge ofits passengers. The elevator doors are then closed and further operationis impossible until the trouble has been remedied.

The novel probe member 22 characterizing the present invention issuspended from the upper portion of the reservoir housing 13, as shown,and it will be noted that the electrodes 24-25 extend downwardly to apoint closely adjacent the bottom of the oil return reservoir. Thus, inthe event there is a minor amount of Water at the bottom of saidreservoir and a relatively larger quantity of oil floating on topthereof, said electrodes will nonetheless detect the presence of thewater. As an additional precautionary feature, the oil inlet (not shown)for the pump 18 is positioned a substantial distance above the bottom ofsaid reservoir to ensure that only the oil floating on the top thereofwill be pumped back into the power unit hydraulic system if there iswater in the reservoir.

From the foregoing detailed description it will be seen that the presentinvention provides a novel safety device for hydraulic elevators whichis an important advancement in the art. As hereinbefore mentioned, manyhydraulic elevators in present use include means for collecting andreturning leakage oil to the power unit hydraulic system in order toensure that there is always a sufficient quantity of oil to permit safeoperation of the elevator, but heretofore there has been no means toprotect against the entry of water into the oil system. Such water,Whether it be condensate or surface water, can saponify the oil andimpede the operation of the elevator, and can result in a disastrousaccident. In accordance with the present invention, however, a sensingdevice is provided to detect the presence of water in the oil returnreservoir, and to automatically prevent the operation of the oil returnpump while simultaneously halting the elevator until necessarycorrective measures can be taken to remedy the situation.

A further advantage of the present invention is that in the event thebasement of the building is being inundated by flood water or a burstwater main or the like, the presence of such water in the oil reservoirwill be immediately detected by the sensing probe and the halting of theelevator will give early Warning of the trouble, thereby permitting thehigh voltage junction boxes and other elec trical components to beremoved from the area before they are immersed in water and ruined, orbefore someone is accidentally electrocuted.

Still further advantages of the present invention are that it iscompletely reliable in operation, and it is relatively inexpensive indesign and construction.

It is to be understood, of course, that the invention is not to belimited or confined to a structure identical in all respects to thatillustrated and hereinbefore described. It is contemplated that numerousvariations or modifications could be made therein while stillincorporating the basic novelty of said invention, and it is intended toinclude herein not only the illustrated embodiment of the invention butalso any and all modifications or variations both in the structure andintended uses thereof as may come within the spirit of said invention,and within the scope of the following claims.

What I claim is:

1. In a hydraulic power system including an oil reservoir, means fordetecting the presence of water in said reservoir comprising: a probeelement in said oil reservoir, said probe having a pair of spacedelectrodes adapted to be immersed or partially immersed in a liquidcontained in said reservoir; means connecting said probe electrodes to asource of electricity to permit a current to be passed between saidelectrodes, the greater elec trical conductivity of water as compared tooil causing an increased current flow therebetween when said electrodesare immersed or partially immersed in water rather than oil; andelectric sensing means operatively connected to said probe and adaptedto detect the increased current flow through said probe electrodes inthe event water is present in said .oil reservoir.

2. In an elevator having a hydraulic power system, and having an oilreturn reservoir adapted to collect oil which leaks from said hydraulicsystem, there being a pump for pumping oil collected in said reservoirback into said hydraulic power sysem, a safety device for preventing theentry of Water into said hydraulic system, comprising: a probe elementin said oil return reservoir, said probe having a pair of spacedelectrodes adapted to be immersed or partially immersed in a liquidcollected in said reservoir; electrical lead wires connecting said probeelectrodes to a source of electricity to permit a current to be passedbetween said electrodes, the greater electrical conductivity of water ascompared to oil causing an increased current flow therebetween when saidelectrodes are immersed or partially immersed in water rather than oil;and electric control means operatively connected to said probe andadapted to be actuated by the increased current flow through said probeelectrodes in the event of water in the oil reservoir to prevent theoperation of said oil return pump.

3. The safety device recited in claim 2 and including means associatedwith said electric control means adapted to automatically halt theoperation of the elevator in the event Water is present in said oilreservoir.

4. The safety device recited in claim 2 wherein said probe elementincludes a hollow insulating body within which said lead wires arecarried, and said probe electrodes being formed of flat,vertically-disposed parallel arms.

5. The safety device recited in claim 2 wherein said 3,302,753 5 6 probeelectrodes extend downwardly to a point adjacent References Cited by theExaminer the bottom of the reservoir, whereby said probe Will UNITEDSTATES PATENTS detect the presence of even a relatively small quantity2,981,196 4/1961 Zimmermann of Water 1n sa1d reservoir.

l t 6. The safety device recited in claim 2 wherein said 5 3O419767/1962 {Maynard 1 6 oil return pump is provided with an inlet openingspaced EVON BLUNK Pnmary Emmme a substantial distance above the bottomof the reservoir. H, C, HORNSBY, Assistant Examiner.

1. IN A HYDRAULIC POWER SYSTEM INCLUDING AN OIL RESERVOIR, MEANS FORDETECTING THE PRESENCE OF WATER IN SAID RESERVOIR COMPRISING: A PROBEELEMENT IN SAID OIL RESERVOIR, SAID PROBE HAVING A PAIR OF SPACEDELECTRODES ADAPTED TO BE IMMERSED OR PARTIALLY IMMERSED IN A LIQUIDCONTAINED IN SAID RESERVOIR; MEANS CONNECTING SAID PROBE ELECTRODES TO ASOURCE OF ELECTRICITY TO PERMIT A CURRENT TO BE PASSED BETWEEN SAIDELECTRODES, THE GREATER ELECTRICAL CONDUCTIVITY OF WATER AS COMPARED TOOIL CAUSING AN INCREASED CURRENT FLOW THEREBETWEEN WHEN SAID ELECTRODESARE IMMERSED OR PARTIALLY IMMERSED IN WATER RATHER THAN OIL; ANDELECTRIC SENSING MEANS OPERATIVELY CONNECTED TO SAID PROBE AND ADAPTEDTO DETECT THE INCREASED CURRENT FLOW THROUGH SAID PROBE ELECTRODES INTHE EVENT WATER IS PRESENT IN SAID OIL RESERVOIR.